Radio

I  INTRODUCTION

Radio Frequency and Wavelength Ranges

Radio waves have a wide range of applications, including communication during emergency rescues (transistor and shortwave radios), international broadcasts (satellites), and cooking food (microwaves). A radio wave is described by its wavelength, the distance from one crest to the next, or its frequency, the number of crests that move past a point in one second. Wavelengths of radio waves range from 100,000 m (270,000 ft) to 1 mm (.004 in). Frequencies range from 3 kilohertz to 300 gigahertz.

Radio, system of communication employing electromagnetic waves propagated through space. Because of their varying characteristics, radio waves of different lengths are employed for different purposes and are usually identified by their frequency. The shortest waves have the highest frequency, or number of cycles per second; the longest waves have the lowest frequency, or fewest cycles per second. In honor of the German radio pioneer Heinrich Hertz, his name has been given to the cycle per second (hertz, Hz); 1 kilohertz (kHz) is 1000 cycles per sec, 1 megahertz (MHz) is 1 million cycles per sec, and 1 gigahertz (GHz) is 1 billion cycles per sec. Radio waves range from a few kilohertz to several gigahertz. Waves of visible light are much shorter. In a vacuum, all electromagnetic waves travel at a uniform speed of about 300,000 km (about 186,000 mi) per second. For electromagnetic waves other than radio.

Radio waves are used not only in radio broadcasting but in wireless telegraphy, two-way communication for law enforcement, telephone transmission, wireless Internet, television, radar, navigational systems, GPS, and space communication. In the atmosphere, the physical characteristics of the air cause slight variations in velocity, which are sources of error in such radio-communications systems as radar. Also, storms or electrical disturbances produce anomalous phenomena in the propagation of radio waves. 

Because electromagnetic waves in a uniform atmosphere travel in straight lines and because the earth's surface is approximately spherical, long-distance radio communication is made possible by the reflection of radio waves from the ionosphere. Radio waves shorter than about 10 m (about 33 ft) in wavelength—designated as very high, ultrahigh, and superhigh frequencies (VHF, UHF, and SHF)—are usually not reflected by the ionosphere; thus, in normal practice, such very short waves are received only within line-of-sight distances. Wavelengths shorter than a few centimeters are absorbed by water droplets or clouds; those shorter than 1.5 cm (0.6 in) may be absorbed selectively by the water vapor present in a clear atmosphere.

A typical radio communication system has two main components, a transmitter and a receiver. The transmitter generates electrical oscillations at a radio frequency called the carrier frequency. Either the amplitude or the frequency itself may be modulated to vary the carrier wave. An amplitude-modulated signal consists of the carrier frequency plus two sidebands resulting from the modulation. Frequency modulation produces more than one pair of sidebands for each modulation frequency. These produce the complex variations that emerge as speech or other sound in radio broadcasting, and in the alterations of light and darkness in television broadcasting.

II TRANSMITTER

Essential components of a radio transmitter include an oscillation generator for converting commercial electric power into oscillations of a predetermined radio frequency; amplifiers for increasing the intensity of these oscillations while retaining the desired frequency; and a transducer for converting the information to be transmitted into a varying electrical voltage proportional to each successive instantaneous intensity. For sound transmission a microphone is the transducer; for picture transmission the transducer is a photoelectric device. 

Other important components of the radio transmitter are the modulator, which uses these proportionate voltages to control the variations in the oscillation intensity or the instantaneous frequency of the carrier, and the antenna, which radiates a similarly modulated carrier wave. Every antenna has some directional properties, that is, it radiates more energy in some directions than in others, but the antenna can be modified so that the radiation pattern varies from a comparatively narrow beam to a comparatively even distribution in all directions; the latter type of radiation is employed in broadcasting.

The particular method of designing and arranging the various components depends on the effects desired. The principal criteria of a radio in a commercial or military airplane, for example, are light weight and intelligibility; cost is a secondary consideration, and fidelity of reproduction is entirely unimportant. In a commercial broadcasting station, on the other hand, size and weight are of comparatively little importance; cost is of some importance; and fidelity is of the utmost importance, particularly for FM stations rigid control of frequency is an absolute necessity. In the U.S., for example, a typical commercial station broadcasting on 1000 kHz is assigned a bandwidth of 10 kHz by the Federal Communications Commission, but this width may be used only for modulation; the carrier frequency itself must be kept precisely at 1000 kHz, for a deviation of one-hundredth of 1 percent would cause serious interference with even distant stations on the same frequency.

A Oscillators

In a typical commercial broadcasting station the carrier frequency is generated by a carefully controlled quartz-crystal oscillator. The fundamental method of controlling frequencies in most radio work is by means of tank circuits, or tuned circuits, that have specific values of inductance and capacitance, and that therefore favor the production of alternating currents of a particular frequency and discourage the flow of currents of other frequencies. In cases where the frequency must be extremely stable, however, a quartz crystal with a definite natural frequency of electrical oscillation is used to stabilize the oscillations. The oscillations are actually generated at low power by an electron tube and are amplified in a series of power amplifiers that act as buffers to prevent interaction of the oscillator with the other components of the transmitter, because such interaction would alter the frequency. The crystal is shaped accurately to the dimensions required to give the desired frequency, which may then be modified slightly by adding a condenser to the circuit to give the exact frequency desired. In a well-designed circuit, such an oscillator does not vary by more than one-hundredth of 1 percent in frequency. Mounting the crystal in a vacuum at constant temperature and stabilizing the supply voltages may produce a frequency stability approaching one-millionth of 1 percent. Crystal oscillators are most useful in the ranges termed very low frequency, low frequency, and medium frequency (VLF, LF, and MF). When frequencies higher than about 10 MHz must be generated, the master oscillator is designed to generate a medium frequency, which is then doubled as often as necessary in special electronic circuits. In cases where rigid frequency control is not required, tuned circuits may be used with conventional electron tubes to generate oscillations up to about 1000 MHz, and reflex klystrons are used to generate the higher frequencies up to 30,000 MHz. Magnetrons are substituted for klystrons when even larger amounts of power must be generated. 

B  Modulation

 

Radio Modulation

Audio-frequency waves must be combined with carrier waves in order to be transmitted over the radio. Either the frequency (rate of oscillation) or the amplitude (height) of the waves may be modified in a process called modulation. This accounts for the option on the radio dial for AM or FM stations; the signals are very different, so both kinds may not be received simultaneously.

Modulation of the carrier wave so that it may carry impulses is performed either at low level or high level. In the former case the audio-frequency signal from the microphone, with little or no amplification, is used to modulate the output of the oscillator, and the modulated carrier frequency is then amplified before it is passed to the antenna; in the latter case the radio-frequency oscillations and the audio-frequency signal are independently amplified, and modulation takes place immediately before the oscillations are passed to the antenna. The signal may be impressed on the carrier either by frequency modulation (FM) or amplitude modulation (AM).

The simplest form of modulation is keying, interrupting the carrier wave at intervals with a key or switch used to form the dots and dashes in continuous-wave radiotelegraphy.

The carrier wave may also be modulated by varying the amplitude, or strength, of the wave in accordance with the variations of frequency and intensity of a sound signal, such as a musical note. This form of modulation, AM, is used in many radiotelephony services including standard radiobroadcasts. AM is also employed for carrier current telephony, in which the modulated carrier is transmitted by wire, and in the transmission of still pictures by wire or radio. 

In FM the frequency of the carrier wave is varied within a fixed range at a rate corresponding to the frequency of a sound signal. This form of modulation, perfected in the 1930s, has the advantage of yielding signals relatively free from noise and interference arising from such sources as automobile-ignition systems and thunderstorms, which seriously affect AM signals. As a result, FM broadcasting is done on high-frequency bands (88 to 108 MHz), which are suitable for broad signals but have a limited reception range.

Carrier waves can also be modulated by varying the phase of the carrier in accordance with the amplitude of the signal. Phase modulation, however, has generally been limited to special equipment.

The development of the technique of transmitting continuous waves in short bursts or pulses of extremely high power introduced the possibility of yet another form of modulation, pulse-time modulation, in which the spacing of the pulses is varied in accordance with the signal.

The information carried by a modulated wave is restored to its original form by a reverse process called demodulation or detection. Radio waves broadcast at low and medium frequencies are amplitude modulated. At higher frequencies both AM and FM are in use; in present-day commercial television, for example, the sound may be carried by FM, while the picture is carried by AM. In the superhigh-frequency range (above the ultrahigh-frequency range), in which broader bandwidths are available, the picture also may be carried by FM.

Digital radio (also called HD or high-definition radio) processes sounds into patterns of numbers instead of into patterns of electrical waves and can be used for both FM and AM broadcasts. The sound received by a radio listener is much clearer and virtually free from interference. The signals can be used to provide additional services, multiple channels, and interactive features. Satellite radio is also a form of digital radio but the signal is broadcast from communication satellites in orbit around Earth and not from local broadcast towers.

C Antennas

The antenna of a transmitter need not be close to the transmitter itself. Commercial broadcasting at medium frequencies generally requires a very large antenna, which is best located at an isolated point far from cities, whereas the broadcasting studio is usually in the heart of the city. FM, television, and other very-high-frequency broadcasts must have very high antennas if appreciably long range is to be achieved, and it may not be convenient to locate such a high antenna near the broadcasting studio. In all such cases, the signals may be transmitted by wires. Ordinary telephone lines are satisfactory for most commercial radio broadcasts; if high fidelity or very high frequencies are required, coaxial or fiber optic cables are used.

III RECEIVERS

Components in a Transistor Radio

This circuit board illustrates the complexity of the modern radio receiver. The six black rectangular components are the Integrated Circuits (ICs) which contain hundreds of transistors. The remaining components are resistors (small, flat, round objects), capacitors (tall, black cylinders), and inductors (coils of wire). Newer circuits have fewer parts, often only one IC and a few resistors. These improvements are due to the development of more advanced ICs and the shift from LC (inductor-capacitor) tuning to PLL (phase-locked loop) tuning. The latter, in addition to providing a digital display of the frequency, requires no discrete components.

The essential components of a radio receiver are an antenna for receiving the electromagnetic waves and converting them into electrical oscillations; amplifiers for increasing the intensity of these oscillations; detection equipment for demodulating; a speaker for converting the impulses into sound waves audible by the human ear (and in television a picture tube for converting the signal into visible light waves); and, in most radio receivers, oscillators to generate radio-frequency waves that can be “mixed” with the incoming waves.

The incoming signal from the antenna, consisting of a radio-frequency carrier oscillation modulated by an audio-frequency or video-frequency signal containing the impulses, is generally very weak. The sensitivity of some modern radio receivers is so great that if the antenna signal can produce an alternating current involving the motion of only a few hundred electrons, this signal can be detected and amplified to produce an intelligible sound from the speaker. Most radio receivers can operate quite well with an input from the antenna of a few millionths of a volt. The dominant consideration in receiver design, however, is that very weak desired signals cannot be made useful by amplifying indiscriminately both the desired signal and undesired radio noise. Thus, the main task of the designer is to assure preferential reception of the desired signal.

Most modern radio receivers are of the superheterodyne type in which an oscillator generates a radio-frequency wave that is mixed with the incoming wave, thereby producing a radio-frequency wave of lower frequency; the latter is called intermediate frequency. To tune the receiver to different frequencies, the frequency of the oscillations is changed, but the intermediate frequency always remains the same (at 455 kHz for most AM receivers and at 10.7 MHz for most FM receivers). The oscillator is tuned by altering the capacity of the capacitor in its tank circuit; the antenna circuit is similarly tuned by a capacitor in its circuit. One or more stages of intermediate-frequency amplification are included in all receivers; in addition, one or more stages of radio-frequency amplification may be included. Auxiliary circuits such as automatic volume control (which operates by rectifying part of the output of one amplification circuit and feeding it back to the control element of the same circuit or of an earlier one) are usually included in the intermediate-frequency stage. The detector, often called the second detector, the mixer being called the first detector, is usually simply a diode acting as a rectifier, and produces an audio-frequency signal. FM waves are demodulated or detected by circuits known as discriminators or radio-detectors that translate the varying frequencies into varying signal amplitudes.

Digital and satellite radio require special receivers that can change a digital signal into analog sound. The digital signal can carry additional information that can be displayed on a screen on the radio. The title of a music track and the artist can be provided, for example. Some radios can even record songs in MP3 format.

A Amplifiers

Radio-frequency and intermediate-frequency amplifiers are voltage amplifiers, increasing the voltage of the signal. Radio receivers may also have one or more stages of audio-frequency voltage amplification. In addition, the last stage before the speaker must be a stage of power amplification. A high-fidelity receiver contains both the tuner and amplifier circuits of a radio. Alternatively, a high-fidelity radio may consist of a separate audio amplifier and a separate radio tuner.

The principal characteristics of a good radio receiver are high sensitivity, selectivity, fidelity, and low noise. Sensitivity is primarily achieved by having numerous stages of amplification and high amplification factors, but high amplification is useless unless reasonable fidelity and low noise can be obtained. The most sensitive receivers have one stage of tuned radio-frequency amplification. Selectivity is the ability of the receiver to obtain signals from one station and reject signals from another station operating on a nearby frequency. Excessive selectivity is not desirable, because a bandwidth of many kilohertz is necessary in order to receive the high-frequency components of the audio-frequency signals. A good broadcast-band receiver tuned to one station has a zero response to a station 20 kHz away. The selectivity depends principally on the circuits in the intermediate-frequency stage.

B High-Fidelity Systems

Fidelity is the equality of response of the receiver to various audio-frequency signals modulated on the carrier. Extremely high fidelity, which means a flat frequency response (equal amplification of all audio frequencies) over the entire audible range from about 20 Hz to 20 kHz, is extremely difficult to obtain. A high-fidelity system is no stronger than its weakest link, and the links include not only all the circuits in the receiver, but also the speaker, the acoustic properties of the room in which the speaker is located, and the transmitter to which the receiver is tuned. Most AM radio stations do not reproduce faithfully sounds below 100 Hz or above 5 kHz; FM stations generally have a frequency range of 50 Hz to 15 kHz, the upper limit being set by Federal Communications Commission regulations. Digital and satellite radio can provide even better high fidelity over a larger range of frequencies. Digital FM approaches the sound quality of CDs. Digital AM radio should be comparable to regular FM in sound quality.

C Distortion

A form of amplitude distortion is often introduced to a radio transmission by increasing the relative intensity of the higher audio frequencies. At the receiver, a corresponding amount of high-frequency attenuation is applied. The net effect of these two forms of distortion is a net reduction in high-frequency background noise or static at the receiver. Many receivers are also equipped with user-adjustable tone controls so that the amplification of high and low frequencies may be adjusted to suit the listener's taste. Another source of distortion is cross modulation, the transfer of signals from one circuit to another through improper shielding. Harmonic distortion caused by nonlinear transfer of signals through amplification stages can often be significantly reduced by the use of negative-feedback circuitry that tends to cancel most of the distortion generated in such amplification stages.

D Noise

Noise is a serious problem in all radio receivers. Several different types of noise, each characterized by a particular type of sound and by a particular cause, have been given names. Among these are hum, a steady low-frequency note (about two octaves below middle C) commonly produced by the frequency of the alternating-current power supply (usually 60 Hz) becoming impressed onto the signal because of improper filtering or shielding; hiss, a steady high-frequency note; and whistle, a pure high-frequency note produced by unintentional audio-frequency oscillation, or by beats. These noises can be eliminated by proper design and construction. Certain types of noise, however, cannot be eliminated. The most important of these in ordinary AM low-frequency and medium-frequency sets is static, caused by electrical disturbances in the atmosphere. Static may be due to the operation of nearby electrical equipment (such as automobile and airplane engines), but is most often caused by lightning. Radio waves produced by such atmospheric disturbances can travel thousands of kilometers with comparatively little attenuation, and inasmuch as a thunderstorm is almost always occurring somewhere within a few thousand kilometers of any radio receiver, static is almost always present. Static affects FM receivers to a much smaller degree, because the amplitude of the intermediate waves is limited in special circuits before discrimination, and this limiting removes effects of static, which influences the signal only by superimposing a random amplitude modulation on the wave. Digital and satellite radio greatly reduces static.

Another basic source of noise is thermal agitation of electrons. In any conductor at a temperature higher than absolute zero, electrons are moving about in a random manner. Because any motion of electrons constitutes an electric current, this thermal motion gives rise to noise when amplification is carried too far. Such noise can be avoided if the signal received from the antenna is considerably stronger than the current caused by thermal agitation; in any case, such noise can be minimized by suitable design. A theoretically perfect receiver at ordinary temperatures can receive speech intelligibly when the signal power in the antenna is only 4 × 10^-18 W (40 attowatts); in ordinary radio receivers, however, considerably greater signal strength is required.

E Power Supply

A radio has no moving parts except the speaker cone, which vibrates within a range of a few thousandths of a centimeter, and so the only power required to operate the radio is electrical power to force electrons through the various circuits. When radios first came into general use in the 1920s, most were operated by batteries. Although batteries are used widely in portable sets today, a power supply from a power line has advantages, because it permits the designer more freedom in selecting circuit components. If the alternating-current (AC) power supply is 120 V, this current can be led directly to the primary coil of a transformer, and power with the desired voltage can be drawn off as desired from the secondary coils. This secondary current must be rectified and filtered before it can be used because transistors require direct current (DC) for proper operation. Electron tubes require DC for plate current; filaments may be heated either by DC or AC, but in the latter case hum may be created. Transistorized radios do not require as high an operating DC voltage as did tube radios of the past, but power supplies are still needed to convert the AC voltage distributed by utility companies to DC, and to step up or step down the voltage to the required value, using transformers. Airplane and automobile radio sets that operate on 12 to 24 volts DC often contain circuits that convert the available DC voltage to AC, after which the voltage is stepped up or down to the required voltage level and again converted to DC by a rectifier. Airplane and automobile radio sets that operate on 6 to 24 volts DC always contain some such device for raising the voltage. The advent of transistors, integrated circuits, and other solid-state electronic devices, which are much smaller in size and require very little power, has today greatly reduced the use of vacuum tubes in radio, television, and other types of communications equipment and devices.

IV HISTORY

Although many discoveries in the field of electricity were necessary to the development of radio, the history of radio really began in 1873, with the publication by the British physicist James Clerk Maxwell of his theory of electromagnetic waves.

A  Late 19th Century

 

Guglielmo Marconi

Inventor of the radio-signaling system, Italian electrical engineer Guglielmo Marconi was the first to send wireless signals across the ocean. Prior to his invention, there was no way to communicate over long distances without telegraph wires to carry electric signals. His equipment played a vital role in rescuing survivors of sea disasters such as the sinking of the Titanic. He won the Nobel Prize in physics in 1909 for his work in wireless telegraphy.

Maxwell's theory applied primarily to light waves. About 15 years later the German physicist Heinrich Hertz actually generated such waves electrically. He supplied an electric charge to a capacitor, and then short-circuited the capacitor through a spark gap. In the resulting electric discharge the current surged past the neutral point, building up an opposite charge on the capacitor, and then continued to surge back and forth, creating an oscillating electric discharge in the form of a spark. Some of the energy of this oscillation was radiated from the spark gap in the form of electromagnetic waves. Hertz measured several of the properties of these so-called Hertzian waves, including their wavelength and velocity.

The concept of using electromagnetic waves for the transmission of messages from one point to another was not new; the heliograph, for example, successfully transmitted messages via a beam of light rays, which could be modulated by means of a shutter to carry signals in the form of the dots and dashes of the Morse code. Radio has many advantages over light for this purpose, but these advantages were not immediately apparent. Radio waves, for example, can travel enormous distances; but microwaves (which Hertz used) cannot. Radio waves can be enormously attenuated and still be received, amplified, and detected; but good amplifiers were not available until the development of electron tubes. Although considerable progress was made in radiotelegraphy (for example, transatlantic communication was established in 1901), radiotelephony might never have become practical without the development of electronics. Historically, developments in radio and in electronics have been interdependent.

To detect the presence of electromagnetic radiation, Hertz used a loop of wire somewhat similar to a wire antenna. At about the same time the Anglo-American inventor David Edward Hughes discovered that a loose contact between a steel point and a carbon block would not conduct current, but that if electromagnetic waves were passed through the junction point, it conducted well. In 1879 Hughes demonstrated the reception of radio signals from a spark transmitter located some hundreds of meters away. In these experiments he conducted a current from a voltaic cell through a glass tube filled loosely with zinc and silver filings, which cohered when radio waves impinged on it. The principle was used by the British physicist Sir Oliver Joseph Lodge, in a device called the coherer, to detect the presence of radio waves. The coherer, after becoming conductive, could again be made resistant by tapping it, causing the metal particles to separate. Although far more sensitive than a wire loop in the absence of an amplifier, the coherer gave only a single response to sufficiently strong radio waves of varying intensities, and could thus be used for telegraphy but not for telephony.

The Italian electrical engineer and inventor Guglielmo Marconi is generally credited with being the inventor of radio. Starting in 1895 he developed an improved coherer and connected it to a rudimentary form of antenna, with its lower end grounded. He also developed improved spark oscillators, connected to crude antennas. The transmitter was modulated with an ordinary telegraph key. The coherer at the receiver actuated a telegraphic instrument through a relay, which functioned as a crude amplifier. In 1896 he transmitted signals for a distance exceeding 1.6 km (more than 1 mi), and applied for his first British patent. In 1897 he transmitted signals from shore to a ship at sea 29 km (18 mi) away. In 1899 he established commercial communication between England and France that operated in all types of weather; early in 1901 he sent signals 322 km (200 mi), and later in the same year succeeded in sending a single letter across the Atlantic Ocean. In 1902 messages were regularly sent across the Atlantic, and by 1905 many ships were using radio for communications with shore stations. For his pioneer work in the field of wireless telegraphy, Marconi shared the 1909 Nobel Prize in physics with the German physicist Karl Ferdinand Braun.

During this time various technical improvements were being made. Tank circuits, containing inductance and capacitance, were used for tuning. Antennas were improved, and their directional properties were discovered and used. Transformers were used to increase the voltage sent to the antenna. Other detectors were developed to supplement the coherer with its clumsy tapper; among these were a magnetic detector that depended on the ability of radio waves to demagnetize steel wires; a bolometer that measured the rise in temperature of a fine wire when radio waves are passed through the wire; and the so-called Fleming valve, the forerunner of the thermionic tube, or vacuum tube.

B  20th Century

The modern vacuum tube traces its development to the discovery made by the American inventor Thomas Alva Edison that a current will flow between the hot filament of an incandescent lamp and another electrode placed in the same lamp, and that this current will flow in only one direction. The Fleming valve was not essentially different from Edison's tube. It was developed by the British physicist and electrical engineer Sir John Ambrose Fleming in 1904 and was the first of the diodes, or two-element tubes, used in radios. This tube was then used as a detector, rectifier, and limiter. A revolutionary advance, which made possible the science of electronics, occurred in 1906 when the American inventor Lee De Forest mounted a third element, the grid, between the filament and cathode of a vacuum tube. De Forest's tube, which he called an audion but which is now called a triode (three-element tube), was first used only as a detector, but its potentialities as an amplifier and oscillator were soon developed, and by 1915 wireless telephony had developed to such a point that communication was established between Virginia and Hawaii and between Virginia and Paris.

The rectifying properties of crystals were discovered in 1912 by the American electrical engineer and inventor Greenleaf Whittier Pickard, who pointed out that crystals can be used as detectors. This discovery gave rise to the so-called crystal sets popular about 1920. In 1912 the American electrical engineer Edwin Howard Armstrong discovered the regenerative circuit, by which part of the output of a tube is fed back to the same tube. This and certain other discoveries by Armstrong form the basis of many circuits in modern radio sets.

In 1902 the American electrical engineer Arthur Edwin Kennelly and the British physicist and electrician Oliver Heaviside, independently and almost simultaneously, announced the probable existence of a layer of ionized gas high in the atmosphere that affects the propagation of radio waves. This layer, formerly called the Heaviside or Kennelly-Heaviside layer, is one of several layers in the ionosphere. Although the ionosphere is transparent to the shortest radio wavelengths, it bends or reflects the longer waves. Because of this reflection, radio waves can be propagated far beyond the horizon. Propagation of radio waves in the ionosphere is strongly affected by time of day, season, and sunspot activity. Slight variations in the nature and altitude of the ionosphere, which can occur rapidly, can affect the quality of long-distance reception. The ionosphere is also responsible for skip, the reception at a considerable distance of a signal that cannot be received at a closer point. This phenomenon occurs when the ground ray has been absorbed by the intervening ground and the ionospherically propagated ray is not reflected at an angle sufficiently steep to be received at short distances from the antenna.

C  Short-wave Radio

 

Early Radio

Radio receivers of the 1930s and 1940s were big and heavy in comparison to more compact, modern devices. This was because the less streamlined individual components were wired individually and ran off large, powerful batteries. This view looks through the back of an early radio, showing components such as valves, coils, and the tuning condenser.

Although parts of the various radio bands—short-wave, long-wave, medium-wave, very-high frequency, and ultrahigh frequency—are allocated for a variety of purposes, the term short-wave radio generally refers to radiobroadcasts in the high-frequency range (3 to 30 MHz) beamed for long distances, especially in international communication. Microwave communication via satellite, however, provides signals with superior reliability and freedom from error.

Amateur, or “ham,” radio is also commonly thought of as short-wave, although amateur operators have been allotted frequencies in the medium-wave band, the very-high-frequency band, and the ultrahigh-frequency band as well as the short-wave band. Certain of these frequencies have restrictions designed to make them available to maximum numbers of users.

During the rapid development of radio after World War I, amateur operators executed such spectacular feats as the first transatlantic radio contact (1921). They have also provided valuable voluntary assistance during emergencies when normal communications are disrupted. Amateur radio organizations have launched a number of satellites piggyback with regular launches by the United States, the former Soviet Union, and the European Space Agency. These satellites are usually called Oscar, for Orbiting Satellites Carrying Amateur Radio. The first, Oscar 1, orbited in 1961, was also the first nongovernmental satellite; the fourth, in 1965, provided the first direct-satellite communications between the U.S. and the Soviet Union. More than 1.5 million people worldwide were licensed amateur radio operators in the early 1980s.

The ability to webcast radio programs over the Internet had a major impact on shortwave broadcasting. In the early 2000s the BBC dropped their shortwave radio service to the United States, Canada, Australia, and other developed countries since their programs were available through computers over the World Wide Web. The widespread use of personal computers with Internet access to chat groups and personal Web pages also replaced some of the hobby aspects of amateur radio in popularity.

D  Radio Today

Immense developments in radio communication technology after World War II helped make possible space exploration, most dramatically in the Apollo moon-landing missions (1969-72). Sophisticated transmitting and receiving equipment was part of the compact, very-high-frequency, communication system on board the command modules and the lunar modules. The system performed voice and ranging functions simultaneously, calculating the distance between the two vehicles by measuring the time lapse between the transmission of tones and the reception of the returns. The voice signals of the astronauts were also transmitted simultaneously around the world by a communications network.

In the 1990s cellular radio telephones (cell phones) became one of the most important and widespread uses of radio communication. By the early 21st century, billions of people worldwide had access to telephone service with lightweight portable cell phones capable of communicating worldwide through radio relays and satellite links. Cell phones have become particularly important in developing countries where landlines for telephones often do not exist outside of large cities. In remote rural areas an individual who owns a cell phone may charge a small fee to let others use the phone service. Such phone service can have a major economic impact in impoverished regions, permitting access to banking services, providing information on prices of crops, and creating small-business contacts.

Digital and satellite radio also greatly expanded the possibilities of radio. Not only does digital radio provide superior sound quality, but it permits such additional services as multiple audio-programming channels, on-demand audio services, and interactive features, as well as targeted advertising. Wireless Internet allows users of computers and portable media devices to access the World Wide Web from all kinds of locations. Personal digital assistants (PDAs) also use radio to access e-mail and other services, including GPS information from satellites. The transition to digital television is expected to free up a large part of the radio spectrum previously used to broadcast analog television. These frequencies may be available for many more wireless uses in the future.

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Railroads

I  INTRODUCTION

Railway Control Room

Computerized control rooms allow railroad personnel to monitor activity on many railroad or subway lines simultaneously. Computers have greatly increased the safety and efficiency of rail transportation. This control room coordinates rail activity at Victoria Station in London.

Railroads, roads on which trains of freight and passenger cars, drawn by locomotives, travel on tracks formed by pairs of parallel metal rails . The term railroad is often extended to include the rolling stock, or cars and locomotives, and the land, buildings, and equipment owned or operated in conjunction with the railroad lines. The terms railroad and railway are interchangeable in the United States.

II  RAILS

The precursors of modern railroads were the wagonways, or tramroads (a tram was originally a coal wagon), built in England as early as the 16th century to facilitate the hauling of coal, ore, or stone from mines or quarries to ports or waterways. Although the first wagonways consisted merely of parallel lines of planks, they enabled draft animals to achieve greater speeds and pull much heavier loads than was possible over the bare surfaces of rutted and often muddy roads. Crossties were introduced in early tramroads to hold the timbers that made up the tracks in place. The wooden tracks were soon improved by facing them with strips of iron, and iron wheels on the wagons came into use. In 1767 a British foundry produced the first cast-iron rails, which withstood heavy loads better than iron-faced timbers.

In 1811 a British coal-mine owner was granted a patent on a toothed rail to be traversed by toothed wheels. This rack-and-pinion principle is still applied in auxiliary third rails used in a few railroads, for example, on Pikes Peak in the United States and on some Swiss mountainsides, where cars must be pulled up extremely steep grades.

Modern rails evolved from the edge rails used in northern England at the beginning of the 19th century. Wagons were held on this type of track by flanges extending downward from the inner edges of the wheels. (Many authorities define railroads and railways, in distinction from tramroads, as lines on which the rails are raised above the roadbed.) After the practicability of the locomotive was demonstrated in 1829, and as locomotives replaced horses, mules, and the occasional stationary engines used to pull cars up grades by means of cables, edge rails came into general use.

Rails of various shapes were devised. The prototype of those used today throughout the world, except in Great Britain, was the flat-footed T rail designed in 1830 by the American inventor Robert Livingston Stevens, who was the chief engineer and president of the newly established Camden and Amboy Railroad in New Jersey. In this type of design the T-shaped rail stands on a base broader than the head of the T, forming flanges at each side that permit the rail to be spiked directly to the ties. In the United States today the rail is mounted on metal plates, called tie plates, which are wider than the rail's base and prevent it from cutting into the ties.

The bridge rail, which in cross section formed an inverted U and which fitted over longitudinal timbers, was used on the Great Western Railway in England until 1892. Standard in Britain today is the bullheaded rail, evolved from an I-shaped rail introduced in 1835. In theory the I rail (called a double-headed rail) could be reversed when the upper side became worn, but in practice this economy could not be effected, because the lower part of the rail also became worn by contact with the heavy metal braces, called chairs, that are required to hold the rail in an upright position. The bullheaded rail has a wider, thicker head than the I rail but also must be mounted in chairs, in which it is braced by wooden wedges.

A  Wrought-Iron and Steel Rails

The first improvement on cast-iron rails were rails of wrought iron, introduced in 1820 in England, where the first steel rail was also manufactured. The manufacture of steel rails in the United States began in 1865, and they are now used throughout the world. Metallurgical advances in the 20th century greatly improved the quality of rail steel. Previously, transverse fissures or cracks often developed inside rails during use, until engineers discovered that the flaws from which these cracks spread were formed when rails hot from the rolling mill were cooling. All rails manufactured for use in the United States now undergo a process of controlled cooling and inspection to prevent such defects. Usually they are also hardened at the ends by heat treatment.

Heavier trains requiring stronger track resulted in much heavier rails. The iron rails used in early railroading weighed less than about 20 kg/m (about 40 lb/yd), and the steel rails used at the beginning of the 20th century in many cases were not heavier than about 30kg/m (about 60 lb/yd). In the 1930s rails weighing 50 kg/m (100 lb/yd) or more, or in some instances more than about 65 kg/m (about 130 lb/yd) were used. Rails manufactured today for main-line use may weigh as much as 75.5 to 77 kg/m (152 to 155 lb/yd).

B  Joints

Because each joint is a relatively weak spot in a track, design engineers have reduced the number of joints by lengthening the rails. The customary length when locomotives were introduced was 0.9 m (3 ft), but in the 1830s this was increased to 4.6 or 6.1 m (15 or 20 ft). Early in the 20th century the most common length for rails was 9.1 m (30 ft), and this figure soon became 10 m (33 ft) when 12.2-m (40-ft) freight cars came into general use. To some extent the length of rails has been limited by difficulties in transporting them. Rails 18.3 m (60 ft) long, used on one British railroad as early as 1894, were installed on some United States railroads, others of which have 13.7-m (45-ft) rails.

In the United States rails are often butt-welded together to form lengths as long as 0.4 km (0.25 mi). At first this was done cautiously for fear that expansion and contraction due to temperature changes would cause buckling in great lengths of continuous rail. Experience showed, however, that longitudinal expansion and contraction are not excessive and need not lead to buckling. Techniques were developed for making butt welds as strong as the rails themselves. Where welding is not used, rails are joined by bars bolted to the sides so as to cover the joint. Stevens is credited with inventing the first such joint. On earlier railroads using metal rails, the individual sections were not fastened together in any way.

Advances in track construction in the 20th century included using longer and stronger joint bars and wider tie plates to spread the weight of trains more evenly on the ties. Tie plates with shoulders to brace the rail on either side are used, and nearly all U.S. railroads have special braces called anticreepers, designed to prevent longitudinal displacement.

Beginning in 1925 and continuing at an accelerated rate after that, especially after World War II (1939-1945), the installation of centralized traffic control (CTC) increased track capacity on many railroads and lessened or even eliminated the need for additional pairs of rails. In this system the switches and signals over many kilometers of track are controlled by a single train dispatcher who sits before a panel or switchboard in a control room. On this panel the location of each train is shown automatically on an illuminated diagram. Below the diagram are knobs that control each signal and levers that control each switch on the line. Many railroads began to remove extra main-line tracks after the installation of CTC.

III  GAUGES

The gauge of track is the distance between the inner edges of the rails at points 1.59 cm (0.626 in) below the top of the heads. In the United States, Canada, the United Kingdom, Mexico, Norway, Sweden, and much of continental Europe, the standard gauge is 143.51 cm (56.5 in). Why this measurement became the standard is a matter of speculation. Probably the tradition is inherited from early tramroads built to accommodate wagons with axles 1.5 m (5 ft) long; some of the early edge rails were 4.45 cm (1.75 in) wide at the top, and the installation of such rails on plateways of the traditional width would have resulted in the 143.51-cm gauge.

Throughout most of the 19th century many railroad companies each built track with a different gauge; some gauges were wider than 143.51 cm and some narrower. About 1870 many railroads began to adopt a narrower gauge, usually 0.9 m (3 ft). The arguments in favor of this gauge were that narrower fills and clearances were needed, lighter rails could be used, and a sharper curvature of the tracks was permissible. In 1871, 1,476 km (917 mi) of narrow-gauge track was under construction in the United States. After the so-called railroad panic of 1873, in which the price of railroad stocks fell sharply, railroad construction of all sorts slowed down. Some authorities maintain that the panic accelerated the use of narrow-gauge tracks in the construction that did take place because it was more economical. Freight shipped over long distances, however, had to be transferred from one freight car to another whenever it reached a junction where the rail gauge changed. The excessive cost of handling at junctions between different roads led to the adoption of the standard gauge by almost all U.S. railroads by about 1886. In the years immediately following, mutual agreements to handle one another's rolling stock at fixed rates were worked out by numerous U.S. railroads.

There was little standardization in the early days of railroad construction. As a result, many railroads in different parts of the world use different gauges. Several countries use standard gauge for their railroads, but many use wider or narrower gauges. The lack of standardized rail widths creates problems for international passengers wishing to travel through several countries. If the tracks of neighboring countries are incompatible, passengers have to change trains at border crossings before continuing on their journey.

IV  TIES AND BALLAST

Railroad Tracks and Crossties

Crossties rest in a bed of gravel ballast and support the railroad tracks placed on top. Crossties are made of wood or concrete. The steel tracks are connected to the crossties by metal plates and fasteners.

Crossties, the transverse members that support the rails and hold them in alignment, were originally untreated timbers. Although concrete ties have become more common, the majority of new ties are wood treated with creosote or some other preservative injected under pressure. The use of preservatives has increased the life of ties from 5 or 6 years to 25 or 30 years or more. Advances in track engineering have included increases in the size of ties and in the number used in a given length of track, and the establishment of rigid standards of quality.

Ties are bedded in a layer of ballast, formerly consisting of various materials such as earth or cinders, but today in all main-line tracks consisting of crushed stone or slag in chips of specified size. The angular irregular shape of the fragments ensures a porous mass for good drainage, but at the same time permits interlocking, so that weight is distributed evenly over the roadbed. The depth of ballast under the ties ranges from less than 61 cm (24 in) to 76 cm (30 in).

V  ROADBED AND ROUTE

Inclines and curves in a track limit the speed of trains, and upgrades require high power. A railroad generally follows topographical contours, but in many places the contours are smoothed by excavations, or cuts, and embankments, or fills. Original construction costs are weighed against anticipated operating costs and revenues. Because U.S. railroads were built largely before the economy of the country was fully developed, the original costs were usually kept low. Extensive improvements were necessary in the 20th century to strengthen roadbeds and eliminate or reduce sharp curves and heavy grades to permit higher speeds, heavier loads, and more frequent operation of trains.

Today, a 1 percent grade, or an incline rising 1 m in 100 m of horizontal distance, is considered steep; gradients on heavy-duty lines are usually limited to 0.5 percent. With the coming of fast freight service and of streamlined passenger trains capable of speeds of 160 km/m (100 mph) or more, curves received even more attention than grades. Curvature is described in terms of the angle formed by radii meeting the ends of an arc that subtends a chord 31 m (100 ft) long. The maximum curvature on a given section of line varies, but it is generally set at 1.5 degrees, and in some cases 0.5 degree is the maximum curvature.

To avoid the jolting of trains, simple curves, which are arcs of circles, are approached by easement curves, in which the radius gradually decreases in length. To counteract centrifugal force, which causes a train to lean outward on a curve, the rails are banked; that is, the outside rail is laid higher than the inside rail, the degree of relative elevation depending on the sharpness of the curve and the expected speed of trains.

The roadbed, which is also called the subgrade, must be carefully prepared before track is laid. To ensure stability, fills are built up in layers, each layer of earth, gravel, or other material being packed down thoroughly before the next is added. The sides of both cuts and fills must slope gently enough to prevent slides, the angle depending on the type of material; the sides may be relatively steep if a cut is made through stone. To minimize erosion that might lead to cave-ins, earth sides are often covered with sod or with a thick layer of cinders.

The greatest damage suffered by roadbeds is caused by water. In cuts and sometimes on fills the shoulders of the roadbed are bordered by drainage ditches. Additional ditches intercepting and draining those that parallel the track, or systems of subsurface drainage pipes under the track, are sometimes needed. In some cases the track is laid on concrete slabs supported by timber piles. One way to keep ground moisture from softening roadbeds is to lay a heavy sheet of plastic material between the roadbed and the soil.

Where a railroad crosses depressions deeper than 15 to 18 m (50 to 60 ft), trestles, bridges, or viaducts are commonly used instead of fills. Track-improvement programs generally include the widening of roadbed shoulders and the strengthening of trestles and bridges.

Tunnels are extremely expensive and are therefore avoided when track can be routed around a hill or mountain. Unless a tunnel is cut through solid rock, it must be lined with timber, brick, reinforced concrete, or corrosion-resistant metal. Sometimes a tunnel is built on a slight grade to ensure drainage.

VI  ELECTRIFICATION

In 1895 electric traction, which previously had proved successful on street railways, was introduced on short sections of U.S. railroads, which were then powered by steam-driven locomotives. This innovation was adopted first by the New York, New Haven, and Hartford Railroad and later in the same year by the Pennsylvania Railroad and the Baltimore & Ohio Railroad. At first electric power was used principally in urban areas and especially in tunnels, to eliminate smoke and steam. The electrification of the tracks passing under Park Avenue to enter Grand Central Terminal in New York City was in response to a serious accident that had occurred when the tunnel became filled with smoke. This electrification project, completed in 1907, was undertaken in compliance with a state law requiring railroads to discontinue the use of combustion engines within New York City.

Later, the value of electric traction in mountainous regions was discovered. Electricity provides greater power on grades than can be achieved with steam, and the use of regenerative braking, in which the motor functions as a generator on downgrades, makes for greater safety and also for economy, because the power produced on downgrades is fed into the supply line. Some of the most extensive electrification in the United States was done by the Pennsylvania Railroad on approximately 1,080 km (670 mi) of route, with about 3,620 km (2,250 mi) of track, connecting New York City, Philadelphia, and Washington, D.C., and extending westward to Harrisburg, Pennsylvania. An important consideration underlying the adoption of electric traction in this densely populated area was the need for increased carrying capacity. Because electric locomotives can accelerate more rapidly, faster schedules could be established and more trains could be run on the same track.

In installations made early in the 20th century in the suburbs of New York City, power is distributed by means of a third rail. This method is still used on some railroads, although it limits power to 600 volts and live rail is dangerous. Today, on more than 95 percent of electrified railroads in the world, current is collected from overhead wires. The circuit is completed through the running rails, which must be grounded.

While electric railroads are popular throughout the world, they are less so in the United States. In the 1950s the Great Northern Railroad (now Burlington Northern Santa Fe) removed its electric wires that crossed the Cascade Mountains. Several other major railroads followed suit in the mid-1970s. In 1981 Conrail (which has subsequently been bought by CSX and Norfolk Southern) put its electric freight-train locomotives into storage. Electric train operation became relegated to short utility-owned private railroads, intercity and suburban passenger trains, and subways.

VII  PASSENGER CARS AND SERVICE

 Dining Car Interior

Passengers enjoy champagne aboard the Napa Valley Wine Train, a three-hour tourist train that travels through the winemaking region of Napa Valley, California. Dining cars are found on trains that travel long distances between cities.

The earliest passenger cars, about 5 m (about 15 ft) long and 2 m (7 ft) wide, were virtually stagecoaches with railroad wheels. Soon larger cars with six wheels instead of four were introduced. In the United States, the Baltimore & Ohio was the first railroad to offer passenger service, in 1830, and only three years later this line introduced a car similar to the cars used for the next 100 years. It seated 60 passengers and was mounted on two four-wheeled swiveling trucks. Swiveling trucks permit the car to follow curves more readily and are now used in passenger car construction throughout the world. In the 20th century, six-wheeled trucks became necessary in the United States and Canada to bear the weight of all-steel cars.

Until 1904, passenger cars were made entirely of wood. In that year, cars with steel underframes were introduced on the suburban lines of the Illinois Central Railroad serving Chicago, and they soon came into general use. In the same year the pioneer subway in New York City set an example by introducing all-steel cars. Within a short time such cars appeared on the Long Island Rail Road and on the suburban lines of the New York Central Railroad, and in 1906 the Pennsylvania Railroad put an all-steel car into long-distance service. Within 20 years such cars constituted about one-third of all passenger cars in the United States. After 1930 few passenger cars were built of other materials until lightweight alloys were developed. Steel cars proved safer and more durable than wooden cars, but they increased operating costs by requiring locomotives to pull more weight in carrying the same number of passengers. The lightweight cars, of aluminum alloy or stainless steel, and double-decker coaches, which have two tiers of seats, considerably reduced this ratio.

A U.S. or Canadian passenger car of typical design has a longitudinal central aisle with a row of transverse seats on either side. Each seat usually accommodates two passengers, and in many cars seat backs may be tilted to allow passengers to sleep in a semireclining position. European cars are divided into transverse compartments. These compartments can be entered only from the outside in most of the cars used in local service in many countries. Other trains have a narrow corridor along one side and thus permit passengers to reach lavatories and dining cars during the trip. U.S. sleeping cars and parlor cars, with porter service and individual reserved seats, correspond roughly to European first-class accommodations, and ordinary day coaches correspond to second-class cars.

A  Sleeping Cars

The first sleeping car in the world, a crude affair with tiers of berths along one wall, was introduced in the United States in 1836. In 1859 American inventor George Pullman converted two Alton Railroad coaches into sleeping cars, and in 1864 he patented the first sleeping car of the type that remained standard in the United States for nearly three-quarters of a century. Modern sleeping cars contain a number of individual rooms called roomettes, bedrooms, or compartments. Rooms have toilet facilities, mirrors and electric lights, liberal space for luggage and personal belongings, and individual heating and air-conditioning controls.

B  Amtrak

Passenger service in the United States was greatly improved during the 1930s, when lightweight, streamlined cars, air conditioning, and faster schedules were introduced. Following World War II, however, the passenger train began a long decline in popularity. By the late 1960s, after the railroads lost almost all mail and express business, the end of passenger service appeared near. Congress responded by creating the National Railroad Passenger Corporation (Amtrak) in 1971 to assume responsibility for intercity passenger trains throughout the United States. By most standards, Amtrak succeeded in reviving passenger train service. The number of passengers carried annually rose from 16.6 million in 1972 to 20.2 million in 1986. By 1982, Amtrak had replaced almost all of the aging passenger cars and locomotives it had inherited from several railroads with new or completely rebuilt equipment. Besides owning the rolling stock, Amtrak employs most onboard personnel and pays railroads for the use of their tracks and facilities. Deficits amounting to hundreds of millions of dollars per year are met by congressional appropriations. In 1976 Amtrak purchased trackage between Boston, New York City, and Washington, D.C., from what was then the Penn Central and began to upgrade the property for speeds of at least 190 km/h (about 120 mph). By 2001 Amtrak operated some 440 locomotives and almost 2,200 passenger cars over more than 35,000 route km (22,000 route mi) across the United States. Amtrak carried over 24 million passengers in 2001. A typical overnight Amtrak train includes a baggage car, several coaches, one or more sleeping cars, a dining car, and a lounge car, or a car that combines both dining and lounge facilities. In the western United States, most Amtrak cars contain two levels of coach seats or sleeping space.

Commuter train service around such cities as Boston, Chicago, New York City, Philadelphia, and San Francisco also underwent a renaissance in the 1970s. Old cars were replaced, ridership increased, and most railroads were relieved of responsibility for operating deficits by public agencies.

C  Passenger Service in Other Countries

Talgo Train

The Talgo (Tren Articulado Ligero Goicoechea Oriol) train was first developed in Spain in the 1940s and named after Spanish engineer Alejandro Goicoechea and financier José Luis Oriol. The train design includes lightweight cars with a low center of gravity and only two wheels, all features that greatly improved acceleration and maneuverability. The train shown here is a Talgo III, first introduced in the 1960s.

Leadership in the development of modern passenger trains shifted away from the United States in the second half of the 20th century. In 1965 Japanese National Railways inaugurated high-speed rail service on its electrified Tōkaidō line, serving industrial centers on the east coast of the main Japanese island of Honshū. By 1968 , 60 trains made 160 trips each day over various distances on the 515-km (320-mi) route between Tokyo and Ōsaka, at speeds of 217 km/h (135 mph). Later extensions lengthened the route to 1,136 km (706 mi), from Tokyo to Hakata.

 

German Intercity Express (ICE)

The electrified ICE is Germany’s fastest train, traveling at speeds of 250 km/h (155 mph). ICE routes link many of Germany's major cities and provide efficient and comfortable transportation.

In Europe, both France and the United Kingdom developed their own high-speed services. In 1981, French National Railways began running the train à grande vitesse, or TGV, between Paris and Lyon and between Paris and Geneva, at average speeds of about 270 km/h (about 168 mph) on routes that were built expressly for this service. British Rail, rather than build new routes for fast trains, began to develop the Advanced Passenger Train (APT) to operate over existing tracks. The APT was designed to use special tilting mechanisms that would permit trains to negotiate curves at speeds of up to 210 km/hr (about 130 mph)—far faster than conventional passenger trains are permitted to travel. After numerous delays because of problems with the train's stabilization system, British Rail abandoned the ATP project. Using some elements of APT technology, the High Speed Train 225 was developed. HST 225 service between London and Scotland began in 1984, by which time British Rail was already looking for a more satisfactory replacement.

VIII  FREIGHT CARS AND SERVICE

 

Container Shipping on a Freight Train

Freight trains transport goods such as coal, grains, ore, livestock, liquids, food, and other general merchandise. Large, sealed shipping containers are a common method of packing goods. During transport they ride piggyback on a type of freight car called a flatcar.

Freight can be handled more economically in the United States and Canada than in most other countries because a high proportion of freight is moved in large units for long distances and can therefore be carried in long cars, which have a large capacity. The greater the capacity, the greater the ratio of the payload to the deadweight of the car. For example, a 14.6-m (48-ft) coal car weighing 27 metric tons can carry 77 tons of coal, but a 15.2-m (50-ft) car of similar construction, with a weight of 34 tons (23 percent more), can carry 109 tons of coal (41 percent more).

The aforementioned 77-ton and 109-ton coal cars are among the largest freight cars in general use. A 36- or 45-ton boxcar offers a striking contrast to the freight cars of the early 20th century, when the usual capacity was 9 or 14 tons. In the United Kingdom, where most freight is moved in small consignments on short hauls, most freight cars carry less than 14 tons. Most continental European freight cars are mounted on fixed wheels rather than on swiveling trucks and would be considered small or at best medium sized in the United States. Large cars similar in most respects to American cars are used to a considerable extent, however, in Russia and the other countries that were part of the former Union of Soviet Socialist Republics (USSR), and also in India and Australia and throughout Africa and South America.

 

Railroad Freight Cars

A variety of rail freight cars is visible in this rail yard in Allentown, Pennsylvania. The black tanker car in the middle of the image carries oil or other petroleum products. The white hopper car is used for hauling bulk products such as grain or gravel. The brown and red boxcars are mulitpurpose cars that can carry a wide range of products or materials.

 

Besides boxcars, flatcars, and the open hopper or dump cars used for coal and ore, a variety of specially designed freight cars is made for particular purposes. Large semitrailers are carried piggyback on flatcars 24 m (80 ft) long. Refrigerated cars and, in freezing weather, heated cars, are needed for meat and other perishables. Special cars are provided for live poultry and livestock. Gases such as ammonia; liquids such as gasoline, oil, alcohol, acids, and paints; and also semiliquid or even solid products, including pickles, are often shipped in tank cars. The caboose, the small car that forms the tail end of a freight train, provides shelter and conveniences for the train crew. To permit the conductor to survey the entire train at intervals, the caboose usually has a glassed-in cupola projecting from the roof, but some cabooses have bay windows instead.

Freight service is generally of two types. One type carries bulk commodities, such as coal, grain, or ore, and generally runs from origin to destination without switching, but on no set schedule. The other type of freight service operates on a regular schedule on a set route and carries all types of commodities. Most railroads operate trains containing only piggyback (trailer-on-flatcar) equipment on schedules almost as fast as passenger trains.

Beginning in the 1960s railroads began allowing higher freight-train speeds—up to 112 km/h (70 mph) on some heavily used routes, although 80 km/h (50 mph) is more common. By the early 1980s, however, the industry had discovered that transit time could be shortened more easily by reducing the time that cars spent in yards than by raising speed limits en route.

IX  ADVANCES IN ROLLING-STOCK DESIGN

Among the most important inventions of the 19th century were the air brake and the automatic coupler. Today most American rolling stock is equipped with air brakes, which operate automatically if a coupling between cars breaks or if a leak develops in the compressed-air system. In the 1870s the American inventor Eli Hamilton Janney patented a design for couplers with pivoted knuckles that would interlock automatically when two cars were pushed together and that could be disengaged by means of a lever extending to the side of the car. In 1887 all car builders adopted as a standard a modified form of the Janney coupler. Because public resentment was aroused by the number of men crushed between cars when operating the old link-and-pin couplers by hand, a federal law was passed in 1897 requiring the installation of automatic couplers on all rolling stock. Enforcement was delayed by later legislation, but eventually this law became effective.

Early in the history of railroading, buffers on the ends of cars were introduced to minimize shocks when cars were bumped together. Modern designs make use of friction between two surfaces. On American passenger cars the head of the buffer at each end of the car is a horizontal plate that slides over or under a corresponding plate on the next car to form a connecting platform. In improved types of draft gears connecting couplers with car sills or underframes, sliding-friction devices have superseded springs.

An important 20th-century advance in rolling-stock design was the introduction of roller bearings, which replaced sleeve bearings on car axles.

X  TERMINALS AND YARDS

 

Railroad Yard in Kansas

Railroad yards contain various parallel tracks on which cars are classified according to type or destination. Railroad workers then assemble the sorted cars into newly configured trains, which exit the yard via a main track.

A terminal is an area where individual cars, perhaps arriving from various points, are sorted according to their destinations and assembled in trains. Freight and passenger terminals necessarily include not only stations with offices and various other facilities, but also yards with more or less elaborate systems of tracks and switches. Usually repair shops are provided, and passenger terminals usually include shops, yards, and sheds where cars are cleaned and supplies are put aboard sleeping cars and dining cars. An incoming locomotive, after its train is uncoupled in a receiving yard and drawn away by a switch engine, proceeds to the engine terminal for inspection, repairs, and servicing or storage. In a freight terminal, the train, minus its locomotive and caboose, is pushed into a classification yard where the cars are separated and sorted. On the usual level tracks the cars must be moved by switch engines, but a large and busy terminal may have a hump yard in which the cars are moved by gravity. Newly assembled strings of cars proceed to other yards where they can be loaded or unloaded, repaired, stored, or prepared for departure.

XI  LABOR

About 80 to 85 percent of all railway workers in the United States are represented by labor organizations. Some of these unions include only railway workers; others include workers both from the railways and from other industries. Members of these unions negotiate with the railroads through chosen representatives. In the course of many years of negotiation, and some bloodshed, an extensive and complicated system of rules and regulations governing wage schedules and working conditions was developed.

XII--RAILROADS IN THE UNITED STATES

Before the railroad era the United States had a few tramroads. For example, a tramline was operated in Boston in 1795 to haul brick. The first line that could properly be called a railroad, that is, one with raised track traversed by flanged wheels, was the Granite Line, which was built in Massachusetts in 1826 to bring granite for the Bunker Hill Monument from the quarry to a wharf on the Neponset River. The cars on this short line were moved by gravity and by a team of horses, except on a short incline where power was supplied by a stationary steam engine with a continuous chain.

Some years previously, in 1815, the first railroad charter in the United States had been granted by the state of New Jersey to the inventor John Stevens, father of Robert L. Stevens (the inventor of the T rail) and sometimes called the father of American railroads. John Stevens was the original organizer of the Pennsylvania Railroad but could not finance his project. Actual construction of the rail network in the United States was not begun until 1828, when work was started on the first section of the Baltimore & Ohio. This 20.9-km (13-mi) line was opened to traffic in 1830, when construction of the Mohawk and Hudson Railroad, parent line of the New York Central, was begun. In that year the country had a total of 37 km (23 mi) of railroad in operation. Five years later the national total was 1,767 km (1,098 mi), and by 1848 it had become 9,650 km (5,996 mi), with virtually all of it in states along the Atlantic seaboard. Rails then began to reach into the Middle West, and soon the new towns of the Mississippi River valley were connected with the eastern seaports. News of the discovery of gold in California in 1849 greatly stimulated railroad building, which was favored at that time by general prosperity. Whereas previous construction had proceeded at an average rate of 509 km (316 mi) per year, through the 1850s the annual average was 3,200 km (2,000 mi). Federal aid, in this period extended indirectly through state governments, was important in fostering the boom. The aid was usually in the form of grants of alternate sections of public lands bordering railroad routes. In return, the railroads gave the government substantial reductions in rates.

A--The Spread of Rail Networks

Transcontinental Railroad

Locomotives from the eastern and western United States are depicted here meeting in Promontory, Utah, where crowds gathered to watch the joining of the Union Pacific and Central Pacific railroads on May 10, 1869. This first transcontinental railroad opened the West to supplies and resources from the East and served as the chief means of transportation for settlers in the West.

Public demand for transcontinental rail connections was originally inspired by a proposal made in favor of them in 1836 by the American statesmen John Plumbe and Robert John Walker. The public demand was increased by the California gold rush of 1849 and by fear that the Pacific Northwest would be annexed to Canada. The need for transcontinental lines was felt so urgently by many influential people that construction of the Union Pacific Railroad was begun during the American Civil War (1861-1865), when railroad building in the East and the Middle West came to a standstill. In 1862 extensive federal land grants had been made directly to the Union Pacific and several other railroad companies. The rails of the Union Pacific, reaching westward from Omaha, Nebraska, and those of the Central Pacific Railroad, reaching eastward from Sacramento, California, were joined at Promontory, Utah, in 1869, completing the coast-to-coast connection.

The inflation of money following the Civil War hampered railroad development for a year or two, but a spurt of extraordinarily rapid growth followed, chiefly in the Middle West and West. Expansion was virtually halted when the financial panic of 1873 caused the price of railroad stocks to drop to a small fraction of their original value. In the 1880s construction boomed again, and mileage was added at an average rate of more than 11,300 km (7,000 mi) a year. Expansion at varying rates continued through 1910. The trackage added to the American rail network in the rest of the 20th century was negligible; railroad construction was limited largely to double-tracking, addition of sidings, improvement of inadequate tracks, and related projects. After World War I the total remained generally static. Track added by new branch lines was balanced by the track of branch lines abandoned because operation had become unprofitable. In some years there was actually a decrease in the national total. All in all, U.S. railroad route mileage declined from a peak of 409,177 km (254,251 mi) in 1916 to 236,910 km (147,210 mi) in 1996.

While the network of rails was spreading, great financial networks were also developing. Groups of independent railroad companies were consolidated to form railroad systems. The New York, New Haven, and Hartford Railroad, for example, was formed by the consolidation of about 200 originally independent lines. At first consolidation was effected usually by outright mergers of corporations, but in later periods leases and stock purchases were the most common methods. Manipulating stocks became a common method of struggle between powerful rivals.

Although some consolidation occurred in the early days of railroading, it was in the last half of the 19th century, after the Civil War, that the combinations that now dominate American railroading began to appear. In this period, for example, the railroad magnates Cornelius Vanderbilt and his son, William Henry Vanderbilt, formed the New York Central. In the first few years of the 20th century, some railway systems that were already large and complex were joined by stock purchases into enormously powerful railroad empires. The Baltimore & Ohio came temporarily under the control of the Pennsylvania Railroad, which previously had established control of a great network of roads in the East and Middle West. The transcontinental routes to the Northwest were brought into the orbit of J. P. Morgan and Company, and those to the Southwest and to San Francisco came under the control of the American railroad magnate Edward Henry Harriman.

 

Steam Locomotive

Engine No. 44, a Baldwin 2-8-0 steam locomotive engine built in 1921, has two wheels on the leading truck, eight driving wheels, and no trailing truck. The engine works on the Georgetown Loop Railroad and formerly ran in Central America. Diesel-electric locomotives began to replace steam locomotives in the 1930s and 1940s.

By the 1870s public sentiment had been aroused against the railroads because of the power and influence of the growing consolidations and because of certain questionable practices. Railroad commissions with regulatory powers came into being in most of the states, and in 1887 Congress created the Interstate Commerce Commission. In 1904 the U.S. Supreme Court applied the Sherman Antitrust Act to railroads, and in 1906 Congress directed the Interstate Commerce Commission to divorce railroad companies from manufacturing and mining companies. Further consolidation was hampered until the Transportation Act of 1920 was passed, granting permission for mergers under certain conditions.

In the depression years following 1929, railroad earnings fell sharply, and in 1937 companies controlling about one-third of the railroad track in the nation were bankrupt. Extensive reorganization of railroad finances was effected in the following decade, with the result that only about 7 percent of the total track remained in the hands of trustees or receivers. Although U.S. railroads were under federal management and control during World War I and were subject to a number of emergency regulations during World War II, they remained under private ownership.

B--Mid-20th-Century Mergers

Numerous large mergers occurred in the United States beginning in the 1960s. In 1968, the Pennsylvania and New York Central railroads combined to form the Penn Central, to which was later added the New York, New Haven, and Hartford railroad. The Penn Central declared bankruptcy in 1970. In 1976, it and other failed railroads in the Northeast—including the Erie Lackawanna, Lehigh Valley, and Reading—were merged by an act of Congress to form the Consolidated Rail Corporation (Conrail). In 1970, the Great Northern, Northern Pacific, and Burlington merged into Burlington Northern (BN); later, BN absorbed the St. Louis-San Francisco (Frisco) Railroad, becoming the Burlington Northern Santa Fe. The Chesapeake & Ohio, Baltimore & Ohio, and Western Maryland railroads became affiliated into the Chessie System. In 1981 Chessie merged with the Family Lines—a combination of the Seaboard Coast Line, Louisville & Nashville, and Clinchfield—to form CSX Corporation. In 1996 the U.S. government approved the merger of the Union Pacific and the Southern Pacific railroads, and in the late 1990s Conrail’s lines were split between CSX and the Norfolk Southern.

XIII--INTERNATIONAL RAILROADS

Many countries around the world depend heavily on rail systems for moving people and freight. In most countries, the rail systems began under national ownership and operation. While several countries continue to operate national rail systems, others have sold their government rail systems to private companies, a trend known as privatization.

A--Canada

Canadian railroading is dominated by two of the world’s largest rail systems: the privately owned Canadian Pacific (CP) Railway and the formerly government-owned Canadian National (CN) Railways, which was privatized in 1995. Both railroads extend east and west, roughly parallel to the U.S.-Canada border, and serve almost every major city in Canada. CN is Canada’s largest railroad; its track network extends from coast to coast. CN serves the major Canadian ports on the Atlantic and Pacific coasts and the Great Lakes. In conjunction with its St. Lawrence and Hudson Railway, CP also has a coast to coast system.

Full management of passenger service on both lines was taken over in 1978 by VIA Rail Canada, a government corporation. At the end of the 20th century, passenger volumes and service levels continued to decline in the face of high costs and strong competition from other forms of transportation, such as private automobiles and airlines.

There are several other major Canadian railroads, running generally north and south. The Ontario Northland Railway runs from North Bay to Moosonee, Ontario, on James Bay. The Algoma Central Railway, located in Ontario, runs from Sault Ste. Marie to Hearst. BC Rail (formerly Pacific Great Eastern) stretches from North Vancouver, British Columbia, to Fort Nelson in northeastern British Columbia.

Modern commuter rail services are provided in Toronto, Montréal, and Vancouver. There was little change in total track mileage from the 1920s through the early 1970s. Many unprofitable lines were abandoned, but new expanded lines took their place. Beginning in the mid-1970s, overall track mileage began to decrease in Canada.

Physically and operationally, Canada’s railroads are practically identical to those of the United States. Lines of each country extend into the other, and freight and passenger cars are freely interchanged between them. Both major Canadian lines have major corporate holdings and rail operations in the United States. CN owns the Grand Trunk Western from Detroit, Michigan, into Chicago, Illinois. CN also has access to Duluth, Minnesota, through its subsidiary, Duluth Winnipeg and Pacific. CP connects into the United States through ownership of the Soo Line and the Delaware and Hudson Railway. With the implementation of the North American Free Trade Agreement (NAFTA) in 1994, there was a marked shift in traffic volumes from east-west to north-south. The shift in traffic has brought new opportunities to the Canadian lines.

In the 1960s and 1970s, the Canadian systems had more freedom in setting rates and meeting competition than did rail companies in the United States. However, the U.S. Staggers Act of 1980 deregulated much of the U.S. system and gave a competitive advantage to U.S. carriers. In the 1980s and 1990s the Canadian railways faced heavier taxation, less freedom to eliminate unprofitable lines, and stiffer highway competition than railroads in the United States.

B--Latin America

Approximately 75 percent of the railroads in Latin America are concentrated in Argentina, southern and eastern Brazil, and Mexico. The rest is made up of rail systems in Chile, Colombia, Cuba, Uruguay, Bolivia, and Ecuador. Elsewhere in the region, railroads tend to be isolated and short. These short lines generally serve a single specific purpose, such as to connect an inland mine or plantation with a seaport or to bypass an unnavigable section of a river.

Most railroads in Latin America were originally government-owned. Many of them were privatized in the 1990s, mainly in response to inadequate investment, poor service, deferred maintenance, and excessive labor costs during government operation. In 1991, Argentina began a process of turning the government operations over to private companies under 30-year concessions. In return for the right to operate the systems for profit, the companies are required to meet minimum conditions for service levels and investment timetables. Brazil followed Argentina’s lead in 1996.

The National Railways of Mexico (FNM) embarked on a privatization plan in 1995. The FNM was divided into three regional systems, as well as a terminal company serving the greater Mexico City area and a series of short lines. The government sold 50-year concessions for the three regional systems. The investment partners include Mexican and U.S. companies. The Mexican lines garner only about 1 percent of the intercity passenger market, but freight traffic has grown steadily since 1991. By the late 1990s freight trains carried approximately 14 percent of intercity freight.

Cuba has many railroads for its size, including regular passenger and freight lines as well as industrial railways and seasonal lines used for sugarcane production. The government is slowly upgrading the Havana-Santiago de Cuba route for faster train speeds, but the project has been stalled by the economic difficulties the country faces.

Many railroads in South America have features of special interest. The Central Railway of Peru, for example, crosses the Andes at an elevation of more than 4,700 m (15,000 ft)—the highest altitude reached by any standard-gauge railroad in the world.

C--Europe

The railroad systems of most of the major countries of western Europe share a number of characteristics. Most have a long history of government operation and ownership (with minor exceptions) and use standard gauge, except for Spain and Portugal, which use the wider 1.67 m (5.5 ft) gauge. Also, most railroads have a high degree of modernization, resulting partly from the vast destruction of track and trains during World War II. Western European rail systems are fairly integrated among neighboring countries, making travel between countries efficient.

Railways in eastern European countries also share common characteristics: direct government ownership and operation since the end of World War II, standard gauge, an emphasis on serving the needs of heavy industry, and relatively well integrated systems. The collapse of the Soviet Union in 1991 led to increased integration of western and eastern European economies as well as their rail transport systems, most particularly in reunified Germany.

In the 1980s the major western European systems developed frequent-service high-speed passenger systems to compete with air travel. France led with the train à grande vitesse (TGV) projects, followed by efforts in Germany, Italy, and Sweden.

The German Deutsche Bundesbahn (DB) rail system features the high-speed ICE (Intercity Express), which travels at 250 km/h (155 mph). The Italians have pursued higher-speed services with a series of ETR (ElettroTreno Rapido) trains that can travel 300 km/h (190 mph). The Italian double-track high-speed project to join Naples, Rome, Florence, and Milan is progressing slowly, and the Rome-Naples line is not expected to be completed until 2007. The completion of the Channel Tunnel in 1994 provided a direct rail link between France and England and opened opportunities for enhanced passenger and freight traffic between the United Kingdom and the rest of Europe.

D--United Kingdom

The British rail network is one of the world’s oldest. During the 1970s and 1980s significant investments were made in upgrading lines and rolling stock. The high-speed trains (HST, Inter-City 125) of the mid-1970s routinely ran at speeds of 200 km/h (125 mph), demonstrating the feasibility and attractiveness of high-speed passenger service in Europe. In the 1980s, electrified passenger service began on the West Coast Main Line, running at speeds of 225 km/h (140 mph). Express networks also expanded the use of containers on freight trains to meet competition from trucks.

The Railways Act of 1993 called for the nationally owned British Rail (BR) system to be split up and sold off to private operators. By 1997 all operating railway functions were split up under a franchise system consisting of over 70 private companies. The infrastructure (such as the tracks, signals, and other permanent structures) is owned by Railtrack. Three major leasing companies took control of rolling-stock, and 25 other companies operate passenger trains. The bulk of BR’s freight services was sold to the English, Welsh, and Scottish Railway (EWS), a unit of the U.S. operator Wisconsin Central. At the end of the 20th century, freight traffic revived and the EWS was buying new locomotives and cars to accommodate the upswing. EWS was also involved in cross-Channel freight services using the Channel Tunnel.

E--Russia

 

Trains in Siberia

The Trans-Siberian Railroad stretches from Moscow to the port of Vladivostok on the Pacific Ocean. Here, two trains ply the rails through the seemingly endless taiga, or boreal forests, of Siberia

The railroad system of the Soviet Union carried huge volumes of passengers and freight. The transition to a market economy following the breakup of the Soviet Union in 1991 eliminated the guarantee of enormous traffic, and in the 1990s the system had to adapt to increasing competition from other types of transportation, particularly trucking. Nevertheless, the Russian rail system remains the major provider of transport services and is still one of the world’s largest systems. The system operates on the traditional large Russian gauge of 152 cm (5 ft).

The Trans-Siberian Railroad and the Baikal-Amur Mainline (BAM) have long been viewed as having the capacity and capability to become profitable rail container routes from Asia to Europe. However, neither line has yet to meet modest expectations in this regard. At the end of the 20th century a high-speed passenger line was being built between Moscow and Saint Petersburg. Proposals to link Moscow with the European high-speed network through Warsaw, Poland, were likely to remain proposals because of a lack of funds.

F--Asia

Train Travel in Asia

Railroads are the chief mode of transportation in Asia, although the level of development is mixed. Some countries, such as Russia and Japan, have vast, sophisticated networks. Other countries, such as Myanmar (formerly known as Burma) and Bangladesh, have only short, truncated lines. This photo shows a well-used train in India.

The major countries of Asia continue to rely heavily, and in some areas almost exclusively, on railroads for both freight and passenger transportation. Passenger traffic on most systems is particularly heavy because of rapidly increasing populations and the comparative absence of modern highways. Regardless of lack of competition, Asian railways still have the problem of finding funds for modernization and development. Some countries, such as Japan, South Korea, Thailand, and Malaysia, have done a spectacular job of keeping their railroads up to date since the heavy damage inflicted during World War II. Other railways in the region, such as those in Bangladesh, Pakistan, Vietnam, and Cambodia, have fallen into a state of serious neglect through inattention, war, or both.

G--Japan

Unlike other Asian countries, Japan has a substantial number of privately owned railroads, mostly for industrial or suburban commuter services. The Japan Railways Group (JNR) was formed from the dissolution of the government-owned and debt-ridden Japanese National Railways (JNR) in 1987. JNR operates the major part of the country’s rail network. Its passenger lines were distributed geographically among six companies: three on Honshu island (JR East, JR Central, and JR West); and one each on the islands of Hokkaidō, Shikoku, and Kyushu. In 1991, the assets of the high-speed Shinkansen lines, known as “bullet trains,” were distributed among the three main island companies operating them. A seventh group member, Japan Railway Freight Company, operates its own locomotives, freight cars, and terminals and leases track access from the six passenger companies.

Japan’s rail system is highly oriented toward passenger service, with over 80 percent of revenues coming from passenger operations and a major part of that from the Shinkansen lines. The Shinkansen lines represent the single most important development in Japanese railway history and encouraged the development of similar systems in Europe. Japan pioneered the modern high-speed passenger railway with the opening of the Tokaido Shinkansen line between Tokyo and Osaka in 1964. These highly successful high-speed services have an excellent safety record and continue to be extended and developed. Shinkansen lines now operate at speeds of 300 km/h (190 mph).

In addition to the JR Group of companies, there are over 125 private and joint private-government financed railways in Japan. These railways range from major private interurban and suburban systems to individual rural and tourist lines. Japan produces its own rail equipment and exports rail, cars, and locomotives.

H--India

From its first railway in 1853, the Indian Railways has grown to become Asia’s second largest (after China) and the world’s third largest state-owned railway system. Indian Railways is organized as a central government operation under the Indian Railway Board. Indian Railways owns and operates its own electric-locomotive, diesel-locomotive, and passenger-coach factories. It also operates one of the world’s largest railway research organizations.

As elsewhere in Asia, the Indian railroads strive to meet increasing passenger and freight loads resulting from increasing population and expanding industrial and agricultural production. During the 1970s, a modernization program introduced welded rail, radio communications, centralized traffic control, mechanized railroad yards, and containerization into the Indian rail system. However, inadequate funding and a lack of physical resources remain obstacles to modernization.

I--China

Train Travel, China

Chinese railroad engineers overcame significant geographic obstacles to extend train travel to most parts of the country. This train in Gansu Province is on level land, but in many places railroad tracks cut over hills, through mountains, and across deep rivers.

Rail service in China dates back to 1876. Beginning with modern China in 1949 a national system was formed out of a collection of disjointed foreign and special-purpose lines to form main lines that could be linked into a national system. China Railways (CR) continues to create new lines to accommodate rapid growth in transport demand. CR has overtaken India as Asia’s largest system and is second only to the Russian system in size for a system under central management.

CR had concentrated on freight, primarily coal, which accounts for over 40 percent of the tonnage, for many years. Demand for freight service still outstrips capacity by a large margin. In the 1990s the demand for passenger service grew considerably.

The Ministry of Railways controls 14 railway administrations, as well as 34 locomotive and rolling-stock factories through the China National Railway Locomotive and Rolling Stock Industry Corporation. It also controls 17 Railway Civil Engineering construction companies, 4 major rail research organizations, and a large research academy.

Plans for a high-speed passenger line from Beijing to Shanghai are in detailed design phases. The construction of a second main line from Beijing to Guangzhou, primarily for freight traffic, was completed in 1997, relieving congestion on this primary north-south route.

J--Southern Africa

The Republic of South Africa has a well-developed rail system called Spoornet. Spoornet is a commercially run division of a state-owned company. Other rail systems associated with the South African lines extend into or run through Namibia, Lesotho, Botswana, Mozambique, Angola, Zimbabwe, Malawi, Zambia, and the Democratic Republic of the Congo. In most cases, these lines are owned or managed by the countries they serve. The various lines constitute, in effect, a transcontinental rail system for southern Africa.

The major shipping port of Dar es Salaam, Tanzania, is accessible to countries in southern Africa by the Tanzania-Zambia (Tanzam or Tazara) Railway. That railroad is a 1,850-km (1,150-mi) link between Lusaka, Zambia, and Dar es Salaam and was completed in 1975. Most of the other railways outside of South Africa and Zimbabwe are marginal operations, frequently caught up either in fiscal crises or guerrilla warfare.

K--North Africa

The nationalized rail systems of Morocco, Algeria, and Tunisia form a network of coast-hugging lines that extend short distances into the interior. The loose network generally consists of low-traffic lines, with many originally constructed for mining and extraction of other natural resources. Egypt, the Sudan, and Ethiopia also possess separate national systems. These lines extend from coastal ports into the interior of their respective countries, but they are not linked with one another. The railways of northern Africa tend to serve primarily as passenger carriers but are poorly funded.

L--Western Africa

A number of separate railroads serve western Africa, with the largest single system in Nigeria. Most of these lines consist of a main stem running inland from each country’s major port, together with a few branches. Their primary function is the transportation of export and import freight, but they also handle substantial and generally increasing passenger traffic. Except in a few cases, each line is limited to its own country. There are also a number of separate railroads built specifically for hauling ore from mines in the interior to ports on the coast.

M--East Africa

East African Railways, a rail network that was jointly operated by Kenya, Uganda, and Tanzania, broke up in 1977. Each country now administers its own system with varied success. The Tanzania-Zambia (Tanzam or Tazara) Railway between Lusaka, Zambia, and the port of Dar es Salaam, Tanzania, is an important railway in the region as well.

N--Australia and New Zealand

Beginning in 1865, railways in Australia were initially built by the individual state governments, with four different gauges to serve local needs. At the time of construction there was no apparent need for an integrated system. Once the lines reached state borders, the gauge problem became a severe restraint on interstate trade. Australian National Railways, established by the national government in 1975, consolidated the separate state systems and the federal system to form a national network. Three gauges remain in use, however, causing delays and raising transportation costs. Efforts have been made to introduce standard-gauge tracks on major routes, and standard-gauge lines now link every state capital on the mainland. Transcontinental service between Sydney and Freemantle was opened in 1970. Australian National Railways embarked on a program to modernize and standardize rail transportation, and in 1991 the National Rail Corporation was formed to provide interstate freight services using the tracks of the state systems.

The Australian national government has begun privatization of the national railways. The Australian railway industry continues to evolve from a number of separate state government departments into privately owned transport organizations. The national government is working on policies that will regulate and set standards for access to the interstate standard-gauge system. Each state, except Queensland, is dividing its track, freight, and passenger sectors into separate operations with the intent to meet the privatization mandate. Queensland intends to retain an integrated rail system. New South Wales had already separated infrastructure, maintenance activities, passenger, and freight services as independent entities by 1996. By 1997 several private passenger operators were in place, and Tasmania’s railway had been taken over by the Wisconsin Central Corporation. In addition, Australian National Railways was to be put up for bid.

Australia has several isolated private railways for iron ore transport that are among the most efficient heavy-haul operations in the world. All are located in the northwest coastal area. The BHP Iron Ore Railroad, the Hamersley Iron Ore Railway, and Robe River Iron Associates conduct efficient mine-to-port operations.

New Zealand’s rail network covers its two main islands and is operated under the name of Tranz Rail. The government-owned New Zealand Railways, a government department for over 100 years, was restructured during the 1980s in preparation for a sale. The sale was completed to a consortium of local banking interests in 1993. Railway operating expertise comes from the Wisconsin Central Corporation. The nationwide network has seen large gains in productivity, increases in traffic, and substantial profits as a private entity.

Tranz Rail operates urban commuter services in Wellington and Auckland under the name Tranz Metro. It also operates a fleet of three roll-on/roll-off train ferries across Cook Strait between North Island and South Island. Another division, Tranz Link, offers coordinated road, rail, and sea transport.

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